Multicast and broadcast service (MBS) refers generally to sending information to a plurality of receivers. Macrodiversity MBS is a specific type of transmission, in which a plurality of base stations transmit synchronously. When using macrodiversity (MD), a plurality of base stations synchronously transmit at about the same frequency, using about the same waveform, and using about the same framing parameters. Macrodiversity is also referred to as a single frequency network (SFN).
At a receiver, such as a client station, macrodiversity provides a so-called “macrodiversity gain” by combining the synchronous broadcasts transmitted by the base stations—providing at the receiver the macrodiversity gain resulting from the combined waveforms. IEEE-802.16 is just one of the standards that support both MBS and macrodiversity. IEEE 802.16 refers to one or more specifications, such as the Institute of Electrical and Electronic Engineers (IEEE) Standard for Local and metropolitan area networks, Part 16: Air Interface for Fixed Broadband Wireless Access Systems, 1 Oct. 2004, the IEEE Standard for Local and metropolitan area networks, Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems, 26 Feb. 2006, and subsequent revisions and additions to those standards.
FIG. 7 depicts an example of OFDMA frames 710A-D used in connection with a MBS transmission consistent with IEEE 802.16. The OFDMA frames 710A-D include regions, such as MBS regions 712A-D, transmitted in a downlink from a base station to a client station. These regions represent one or more OFDMA symbols (or simply symbols) carrying the content (e.g., packets) of the multicast and broadcast service. When macrodiversity is used, the base stations synchronously transmit an MBS region (e.g., the first symbol of an MBS region is transmitted at about the same time at each of the base stations). In accordance with IEEE 802.16, the MBS regions 712A-D are described by MBS maps 714A-D. The client station uses information in the MBS map as well as other management messages sent from the base station to the client station to decode the data content in the MBS regions to form packets for use at the client station.